AC: Armor Class. Dungeons and Dragons armor defends solely by reducing the chance to hit altogether. It has the somewhat confusing quality of being better as the number decreases. It can be increased with equippable items, such as rings and earrings, and spells such as Armor and Shield. For the effects of armor in other games, see 'Armor', below.

AI: Artificial Intelligence. The code that governs NPC behaviour, whether it be team members or enemy monsters

Aggro or Aggression, the code that directs monsters to pursue and attack targets, and choose which particular players or characters to attack first

AE: Area Effect. Also AoE, Area of Effect. An area, usually a circle of a given radius, usually centered on the target or user (except e.g. for Ground Targeted Area of Effect), in which effects or damage, usually of spells, takes place, or game variables are in effect, such as when the distance between a monster and player character is checked to determine whether the monster will attack the player (Aggro)

Area: Usually, a location in the game. Also see Area of Effect, above.

Armor in games can represent a wide variety of values. It can be a way to absorb a percentage of damage or reduce damage by a set amount. In games like Fallout, armor applies both types of reduction. In D&D, it is represented by Armor Class and Resistances. It was additional HP in the Quake first person shooter (the same effect as the Temporary hit points of spells such as Cloak of Warding and Vampiric Touch)

Blades: Weapon type. Edged weapons were the mainstay of medieval warfare. Damage type is usually called Slashing

Bottleneck; also Choke point: A narrowing of the path that can be used to tactical advantage. Small groups move into the narrow part of the bottleneck, in a line with its members to the left and right of each other, until they fill the entire width of the path. This forces the enemy to engage them along this narrow front with only a small part of its larger numbers. Larger groups can, with a similar rank, fill a larger portion, keeping the enemy in a relatively more confined position, and thus able to engage with relatively fewer units

This works even better in real life than in games, because of the space required to swing a weapon, and undefended blows being killing blows rather than a loss of HP. It does not work at all in games where units cannot attack diagonally on the screen

Bug: Game construction, usually unintended by its developers, but intentional mechanics that are disadvantageous are often mistakenly called Bugs by players. Intentional or unintentional construction that game companies do not wish to change is routinely deemed "working as intended" in order to divert player dissent. If it leads to benefits for players, game company interests and player jealousy usually lead to it being called an Exploit. Strategy that capitalizes on benefits of game construction, usually ones not intended by the developers, or Bugs

Concentration of Fire: A tactic that aids Damage Reduction. A given amount of damage from multiple sources is set against a given amount of damage from another multiple sources. If damage is spread out between targets, then they survive longer to do more damage. If damage (fire) is concentrated on one target at a time, that target and successive targets die sooner, reducing damage. Known as Focus Fire in WoW[1]

Cooldown: The short period of time before a skill can be used again. Spells such as Missile of Patience and Ice Dagger have multiple missiles possible from a single spell, with a cooldown period before the second missile can be used

Critical Hits or critical strikes: Attacks which hit a vital spot and do more damage than normal, especially ones that are made from behind or while using Stealth

Crushing and other names, including Bashing or Blunt: Damage type using blunt instruments and supposed to be better against skeletons, despite the fact that Slashing / Blade / Edged weapons are superior in all respects. Piercing weapons can get between plates of armor, but bashing weapons have always been used in medieval warfare against unarmored opponents, or to beat the opponent to the ground, where they would be finished off with stabbing weapons. Maces are the exception; they are actually piercing weapons which use the weight of the mace to apply force to a tiny area, and can actually puncture armor

Damage over Time, DoT: effects, e.g. Swarm Curse, that deal increments of damage; damage at intervals, repeatedly, and usually for a set duration

Damage type: Slashing, Piercing and Crushing are physical damage types that distinguish weapon damage; the other types, other than Fire and Acid, usually represent magical damage. See any Enemy NPC article for the full list

Deader: Slang term from the Hive culture, to describe dead people or corpses, and metaphors derived thereof. A subject that comes up often in a Ward dominated by the effects of poverty and the influence of the Dustmen

Drop: synonym for Loot, or verb meaning the Spawning of Loot into the game environment

Duration: A set period of time during which a game variable is true and active, e.g. the period during which the AC bonuses of Armor and Shield exist, and the amount of time that Stealth remains active after it is 'broken' by interacting with doors or containers (or by combat; see Baator)

Exploit Strategy that capitalizes on benefits of game construction, usually ones not intended by the developers, or Bugs. The name reflects the judgement by 'legit' players that an advantage that 'exploiting' players choose to use is in some way a detriment to the legit players, which is an entirely subjective viewpoint within game experience, which is always subjective

Fist Weapon type, varying damage; a weapon attached to the wrist and forearm to allow piercing damage with punches and swipes. In RL, a weapon of less finesse than others, because of the inability to employ the movement of the wrist, not more, as is implied by giving them to the skillful weapons expert Thief Annah. It has the advantage of allowing the full force of a blow to travel directly to the target from the arm, possibly punching through armor, but does not benefit from the additional force of the swing, which consideration lead to the development of longer and longer weapons, i.e. polearms

FPS: First person shooter; 3D game, looking through the character's eyes, with a gun

MMO, MMORPG: Massively Multiplayer Online, – Role Playing Game. Games where many players log in to a persistent game world and play the game together

Mob: NPC monsters. Probably originally meant a group of monsters, judging by the name, although it is said it stands for "mobile", when electronic games first became sophisticated enough to display character movement...Yeh, I didn't think so, either

Mod Modifications to a game, unofficial, released by fans. Files created for a game to add functionality or change the trappings of a game, usually created by people not employed by the game developer

Overkill In games with set HP values, Overkill is an amount of damage far exceeding what is necessary to kill the target. Can also be used to describe any other unnecessary measures, especially ones that are quantifiable, such as Overhealing

Patch Modifications to a game, official, released by developer. Files created for a game to add functionality or change the trappings of a game

PC: Player Character, as opposed to NPC. Also Personal Computer. Depends on the context

Piercing: type of damage. Weapons such as rapiers and daggers can strike between plates of armor; the rise in their use, and the use of the piercing spike of polearms such as Halberds, and crossbows and early firearms, all of which could penetrate armor directly, led to the abandonment of full suits of heavy armor towards the end of the Middle Ages, although the use of helms and breastplates for protection of the head and torso continued

Platform: Game type designation based on the hardware required to play the game. e.g. PC (Personal Computer), PS3, Wii, Xbox

Platform game: Timing and spacial awareness are required to navigate these mazes of platforms, precipices, and moving obstacles

Portal: In PS:T, swirling vapour glowing blue and a shimmering fall of glowing white particles mark the disruption of matter by the highly energetic state of these interdimensional pathways that allow the party to Zone

Power, Mana, MP, Magic Points: Spells outside of D&D often have an MP cost with higher spells costing more points. Commonly used in RPGs

Radius: Distance from the center of a circle to its edge, which in games determines the area of effect of damage spells, or other game variables such as the area within which characters can trade items to each other

Resistance: Values that absorb a percentage of incoming damage in D&D set for each Damage type. For Resistance in D&D, PS:T and other games, see Armor and Damage avoidance

Rest: Resting in D&D regains spells as well as hit points, and always takes eight game hours. Resting in Inns can regain more HP. See the Sorcerer's Place[2] and Spells article for the very short list of places where the party can Rest

Spawn: A game entity, usually NPC, being rendered into the game world, or PC being rendered and gaining their interface with the game world

Splash damage: An AE type of damage, usually in addition to normal damage, which surrounds the point at which the normal damage originates, and can usually harm Friendly units

Spawn point: position at which an entity spawns, sometimes fixed to a particular location

Stealth or stealthing; ability which renders its user invisible or near invisible and unable to be attacked until the user attacks. Usually a prerequisite for special attacks that automatically do high amounts of damage and/or an increased chance of Critical Hits. Unlike stealth in other games, PS:T's stealth is not negated entirely after an attack, see the Baator article

Strafe: Originally, in warfare, shooting while moving, then in First Person Shooters, moving sideways while shooting, has come to mean moving sideways in MMOs et al.

Zerg: Overpower with force, especially force of numbers, rather than skill; using large numbers of smaller/weaker resources to achieve a task typically achieved by fewer larger resources

Zone, zoning: Game Area or sub-area, and a verb meaning, to transition between Zones, either with zone transition areas (over which the cursor will transform into a brown cross with arrows on each end), or portals (purple cross), or with dialogue options, as in Ravel's Maze and Baator and with the Modron Cube